Study on SMART Reactor Design Using ThO2-UO2 Fuel

There are two heterogenous core design options for thorium based fuel cycle in PWRs. One of them is Whole Assembly Seed and Blanket (WASB) design. In WASB design, seed units and blanket units separately occupy one full-size PWR assembly each, and the assemblies are arranged in the core in a modified checkerboard array. In this study, the seed units was loaded with UO2 fuel rods and the blanket units was loaded with ThO2-UO2 . The configuration for each assemblies in both seed and blanket units were based on 17x17 KOFA (Korean Standard Fuel Assembly). Neutronics calculation was performed by using PIJ and CITATION modules of SRAC 2006 code with JENDL 3.3 as nuclear data library. The calculation showed that for the same fuel material configuration in each asssembly uints the WASB-I core loading pattern produce a better power distribution than WASB-II core loading pattern. The criticality condition for both core loading patterns can be achieved by loading 4.95 wt.% of enriched-U in seed fuel assemblies while blanket fuel assemblies were loaded by 20 % UO2 (15 wt.% of enriched-U ) and 80% ThO2.